目的：研究平山病患者和非平山病患者钩椎关节在CT上的形态学差异，提出平山病可能的发病机制。方法：选择2006年10月～2012年1月我院骨科诊治的平山病患者32例作为病例组，均为男性，年龄16～37岁，平均19.4±4.1岁；发病年龄14～27岁，平均16.8±2.5岁；病程1～120个月，平均31.7±23.7个月。选取同期因急性颈痛于我院急诊就诊且颈椎CT正常的32例患者为对照组，亦均为男性，年龄12～26岁，平均19.1±4.3岁。两组年龄无统计学差异（P＞0.05）。在GE-PACS系统上选取两组患者通过C3～C7横突孔中心的颈椎CT冠状截面图片，分别测量各节段左右两侧如下指标：①钩突基底宽，椎体上缘的延长线上钩突内外侧缘的间距；②钩突高，钩突尖至椎体上缘延长线的垂直距离；③钩突间距，双侧钩突尖间的直线距离；④钩突倾角，钩突与椎体上缘的夹角；⑤下终板倾角，被测量椎体下终板与同一椎体侧边的夹角。结果：平山病患者C3～C7同一节段左右两侧的钩突基底宽、钩突高、钩突间距、钩突倾角、下终板倾角均无显著性差异（P＞0.05）。平山病患者C3~C7之间的钩突高及钩突间距有显著性差异（P＜0.05），其中钩突高C6最高、C4最低，其递减规律为C6＞C5＞C7＞C3＞C4，同时钩突间距则表现为C3~C7逐渐增宽；钩突基底宽、钩突倾角、上椎体下终板倾角（除C3外）在C3~C7之间无显著性差异（P＞0.05）。两组取左右两侧均值为相应节段的钩突基底宽、钩突高，并计算左右两侧钩突倾角总和、下终板倾角总和及相应节段的倾角总和之差（即钩突倾角总和-下终板倾角总和），再计算均值及标准差。平山病患者C3～C7的钩突基底宽、钩突间距以及钩突倾角总和与对照组比较均无显著性差异（P＞0.05），而同一节段钩突高度和上位椎体下终板倾角总和均明显小于对照组（P＜0.05），且倾角总和之差均显著大于对照组（P＜0.05）。结论：平山病患者可能存在钩椎关节发育异常，表现为钩突的相关指标发育不平衡，同时具有较矮的钩突以及较小的下终板倾角，继而引发的颈椎不稳定在平山病的发生和发展过程中有重要意义。
Objectives: To study the morphological difference of luscka joints between Hirayama disease patients and non-Hirayama disease patients on CT scan and to provide a new possible mechanism of Hirayama disease. Methods: 32 patients(all males) with a mean age of 19.4±4.1(range 16-37 years) and with Hirayama disease were treated in our hospital from October 2006 to January 2012, the mean course of disease was 31.7±23.7 months(range, 1-120 months). 32 patients(all males) with a mean of age was 19.1±4.3 (range, 12-26 years) suffering from acute neck pain and having no Hirayama disease were reviewed as control. Both groups showed no age related difference. From the cervical CT coronal plane reconstruction images which passing through the transverse foramen center of C3-C7 in GE-PACS system, the following data were measured in both sides: ①The width of the uncinate process base: the distance between inner and outer margin of the uncinate process at the upper edge of the vertebral body. ②The height of the uncinate process:the vertical distance from the top of the uncinate process to the upper edge of the vertebral body. ③The distance between two uncinate processes: the distance between the tips of the bilateral uncinate processes. ④The inclination angle of the uncinate process: the angle between the uncinate process and the upper edge of the vertebral body. ⑤The inclination angle of the inferior endplate: the angle between the uncinate process:the vertical distance from the top of the uncinate process to the upper edge of the vertebral body. Results:There were no significant side-related differences on the width of the uncinate process base, the height of the uncinate process, the distance of the uncinate process, the inclination angle of the uncinate process and the inclination angle of the inferior endplate at the same segment from C3 to C7 in Hirayama disease patients(P>0.05). However, differences were found on the height of the uncinate process and the distance between two uncinate processes of C3-C7 (P<0.05), C6 and C4 had the highest and lowest height of the uncinate process as C6>C5>C7>C3>C4. The distance of the uncinate process gradually increased from C3 to C7. There were no significant differences on the width of the uncinate process base, the inclination angle of the uncinate pro-cess and the inclination angle of inferior endplate(except for C3) of C3-C7(P>0.05). Then, using the mean value of the left and right sides as the width of the base of uncinate process, the height of uncinate process, and calculating the sum of inclination angle of the uncinate process, the sum of inclination angle of inferior endplate of the upper vertebra and the difference between the sums (the sum of inclination angle of uncinate process - the sum of inclination angle of inferior endplate of the upper vertebra), then calculating the mean value and standard deviation. Compared with the non-Hirayama disease patients, there were no significant dif-ferences on the uncinate process base, the distance of the uncinate process and the sum of inclination angle of the uncinate process at the same segment of Hirayama disease patients (P>0.05), while the height of the uncinate process and the sum of inclination angle of uncinate process of Hirayama disease patients were sig-nificantly smaller than those of the control group, respectively(P<0.05), and the differences between the sums were larger than those of the control group (P<0.05). Conclusions: Hirayama disease patients may possess a dysplasia in the luscka joint, manifesting the nonuniform development of the uncinate indicators. Lower unci-nate process and smaller inclination angle of inferior endplate of the upper vertebra are common, The conse-quential cervical instability may play a significantly important role in the pathogenesis and progress of Hi-rayama disease.